Protector for one or more electromagnetic sensors

A frequency-selective arrangement for transmission therethrough of electromagnetic radiation around at least one predetermined transmission frequency, the frequency-selective arrangement comprising a plurality of adjacent layers forming a shield for placement in front of at least one antenna arrangement, the shield including at least a first layer and a second layer, the first layer being arranged closer than the second layer to the at least one antenna arrangement, wherein

• the second layer includes two electromagnetic reflecting layers each having a periodic pattern of electrically conductive elements, where said periodic pattern of electrically conductive elements is selected to possess a reflection resonance frequency for electromagnetic radiation which is about three times higher than said predetermined transmission frequency, and
• the first layer includes one electromagnetic transmitting layer placed at a distance from the second layer, which is approximately equal to .lambda./4, .lambda. being the electrical wavelength, said electromagnetic transmitting layer having a periodic pattern of aperture elements, wherein said periodic pattern of aperture elements is selected to possess a transmission resonance frequency for electromagnetic radiation which is substantially equal to said predetermined transmission frequency.